replacing rubber gasket in gas tank cap

[DimitriT]

The circular rubber gasket is dried and cracked. As a result
the cap leaks. If I apply some grease the cap works correctly.
But the grease is not a real solution. It looks like the caps are
available for about $50 but I am wondering if anyone has
found a cheaper solution by replacing the rubber gasket.

[IanFrancisco]

Well, we don't know which bike is being discussed here. The gasket may be available from a dealer or BikeBandit.com. If not you may be able to not replace it but repair it with some kind of gas-proof glue or sealer similar to silicone ATV sealer. I don't think using silicone would be a good idea on the gas cap. Or, you may be able to make an extra gasket to add to the cracked one using an old inner tube. That would certainly not cost much.

[DimitriT]

Sorry for leaving out the specifics. I have an 82 GS550LZ. I went to the auto supply place near us and looked at their gasket material but they didn't have anything which looked like a good fit. I know they sell rolls of rubber gasket material but I'm not sure which one would work, where to get it from, etc.

[LW_Icarus]

inner tube is not petroleum safe, the gas would eat it, presumably making a mess of things. the rubber seal isnt available seperately for my bike, not sure if the cap is available any longer either.

maybe look at advances selection of old style gas caps, and see if one of the seals will work.or try a lawn and garden center and see if they have any fuel fillers with rubber seals.

modern cars (fords volvos and mazdas for sure) use a rubber seal at the gas tank for the drop in pump, they are big, but could be cut down and bonded together, there are special adhesives for use in sealing fuel tanks, also should be available at advance.

this is just stuff that comes to mind right off, I havent had to find a replacement yet for myself, but I have looked for an oem one already.

[IanFrancisco]

My bad for suggesting inner tube...

[mixongw]

Any gasket material made from Nitrile (Buna-N) is the preferred material in a petroleum environment.

[SqDancerLynn1]

I would look for a rubber grease/oil resistant floor mat & cut a piece to make a new gasket

[SqDancerLynn1]

I would look for a rubber grease/oil resistant floor mat & cut a piece to make a new gasket

[LW_Icarus]

In all honesty had I not had a bicycle tire explode once after getting doused,I wouldnt ever have thought twice about it. gasoline makes tires and tubes gooey in pretty short order. as mix said, nitrile rubber is what is used in a petroleum type application. I also agree with both of lynn's suggestions to seek an oilproof mat of some type, Im sure thatd do the trick nicely.

[Macmatic]

Most HomeDepot type stores have a selection of various sheet gasket material in the plumbing department. One of them might be the right type and thickness.

If you have a "pull your own" parts yard near you I'd take your cap in and look at oil filler caps on european and Japanese cars. All of them use a rubber gasket and one of them is bound to be the right size...then just note the make, year and model and head off to an auto parts store.


/\/\ac

[DimitriT]

I picked up a roll of cork/rubber gasket material at AdvanceAuto and cut a ring the same size as the gasket. I then used silicone sealer to glue the ring (about 1/16 thick) to the original. The glue may not have been necessary since the center portion of the cap overlaps onto the gasket and holds everything in place anyway. Total cost $5.49 and I now have enough material for another 50 or so applications.

I really needed to do this as fumes were leaking out the tank and stinking up the garage.

[DCgs450L]

How is the new gasket holding up. I discovered I need to do this as well. I filled my tank and put her on the side stand yesterday. I turned around and saw gas leaking out from under the cap and spilling on the hot engine. 8O The gasket isn't cracked but it is dry and shrunk a bit.

[DimitriT]

so far so good.

No leaks when I tip the tank and the cork/rubber material is
holding up. When I took the cap apart I also applied some
light grease to all the moving parts, disassembled and cleaned
the little air valve.

One thing to look for. When you take the cap off, is there a light
coating of fuel on the inside of the cap (even if the tank is half
full)? I think the coating is due to vapors condensing. If you
don't have that (cap is dry), the fumes are probably leaking out.

[DCgs450L]

I can't remember if it was dry or not. I didn't pay attention until it started leaking. After that of course, I took the cap off and gas drained out of it.

[mixongw]

My 1100 cap has a circular spring washer under the rubber gasket. The gasket seemed to be in good shape but it wasn't sealing. I bent the tabs of the spring washer to provide more tension to the rubber washer and it works fine now.